Long duration call (LDC) charging becomes a critical issue for IMS (IP Multimedia Subsystem) /LTE (Long Term Evolution) network. Currently the data mobile usage trend is clearly oriented towards longer IP-CAN (IP-Connectivity Access Network) sessions. The usage of smart phones and the heterogeneousness of their operating systems behavior with regards to notifications, push mode, etc. increase the number of very long sessions in telecommunication networks. In addition, the 4G LTE/EPC (Evolved Packet Core) achieves the always on IP connectivity feature and IP-CAN sessions will remain active even for months from attachment to detachment.
However, for an IP-CAN session, if the charging session is kept when there is no active service or data flow within the IP-CAN during long duration session (i.e. the always on IP connectivity session), it is a waste of resources for all charging network elements associated with the IP-CAN.
Currently, various standards and practices tie the charging Diameter session tightly with IP-CAN session, such that a closure of Diameter session will terminate the IP-CAN session at that the PCRF (Policy and Charging Rules Function) will remove all charging rules (Policy and Charging Rules, i.e. PCC rules) related to the IP-CAN session.
Therefore, the prior art cannot implement the following solution: releasing a charging Diameter session, for example, a Gy/Ro session, when there is no active service/data flow, but still keeping the IP-CAN/bearer session, so as to achieve the always on IP connectivity.